1. Field of the Invention
The present invention relates to a mechanical device for the enhancement of a linear force. More particularly, the invention involves a force delivered by a pneumatic cylinder, wherein the load output of the pneumatic cylinder is amplified and, also, wherein there is provided sufficient adjustment of the tool to permit the overall apparatus to be engaged and disengaged with a variety of workpieces requiring a variety of strokes.
2. Description of the Prior Art
The prior art reveals a wide variety of mechanical devices for the enhancement of a force delivered by hand, hydraulic and other means. In general, a small input force is translated into a relatively larger output force. The initial force is commonly generated by the application of a fluid driven device that employs a work medium such as oil or air.
The present invention is an improvement over the force multiplying mechanism shown and described in U.S. Pat. No. 3,680,400 entitled "Force-Multiplying Mechanisms" issued Aug. 1, 1972, to Herbert Lemper et al. The above referenced patent describes a device for -he shearing of metal blooms that are of large cross-sectional area. Consequently, the movable shear blade has to travel a considerable distance in order to effect a clean and complete shearing of the bloom. The power for the shearing action is delivered by a drive shaft that has an eccentrically mounted pitman arm that is coupled to a knife block. The coupling between the pitman arm and the knife block is made by a screw mechanism contained primarily within the knife block. The screw mechanism has an independent power source that is actuated in synchronism with the oscillation of the pitman arm. On the power stroke, the pitman arm advances the shear blade a short distance. Normally, on the return stroke of the pitman arm the shear blade would reverse its direction of travel, however, the screw mechanism within the knife block maintains the position of the shear blade until it can be advanced another incremental distance o the next power stroke of the pitman arm. Thus, there are two forces that are alternatively applied to the knife blade. First, there is the larger force generated by the pitman arm and, second, there is the smaller force applied by the screw mechanism.
The present invention also applies a large and a small force to a tool carrying ram. However, the mechanism employed by the present invention is much simpler than the mechanism set forth in U.S. Pat. No. 3,680,400. Also, the ram of the present invention utilizes a single power source.
U.S. Pat. No. 3,417,599 issued Dec. 24, 1968, entitled "Compressing Tool" to William C. Burns describes and shows a crimping tool that delivers two different loads through the action of a single actuator rod. The actuator rod moves, under the influence of leveraged hand operated handles, to compress a series of Belleville washers. The twin array of Belleville washers delivers a compressive load to one portion of a crimping head. An adjacent portion of the crimping head receives a lesser load because this portion of the crimping head is under the influence of a weaker set of Belleville washers. Thus, a fastener that is subjected to the crimping tool described in U.S. Pat. No. 3,417,599 receives two different crimping forces through the action of the crimping tool handles.
The present invention differs from the hand operated crimper described in U.S. Pat. No. 3,417,599 in that a first load is applied to a ram to move it through a larger distance. A second load is then applied to the ram to move it through a lesser distance. A single pneumatic cylinder rod is utilized to create each of the ram loading conditions.
In U.S. Pat. No. 4,442,581 entitled "Button Puncher or Crimper" issued to Melvin Molnick, a crimping device is shown and described. The crimping device or tool is quite portable and relies primarily on a pantograph configuration for developing a mechanical advantage that permits the jaws of the tool to perform useful work. In one particular embodiment of the invention, shown in FIG. 4, a hydraulic cylinder is used to apply the actuating force to the tool. A mechanical advantage is achieved through the use of a sliding fulcrum point identified by numeral 44. The direction of travel of the fulcrum 44 is linear throughout its entire traverse.
Other linear free enhancement devices are known in the prior art, for example, Benetear, U.S. Pat. No. 4,099,436, teaches an hydraulic piercing device wherein a punch is driven by a cylinder and piston. The arrangement is such that a small pressure applied to a second piston results in a large force applied by the punch to the sheet material. The lower piston is at first activated by compressed hydraulic fluid until it makes contact with the work. The upper piston which is activated by compressed air travels towards the lower piston so that its piston rod entraps the pressurized hydraulic fluid above the lower piston, and proceeds to add its own pressure to the pressure already acting upon the lower piston. The entire action is controlled by a delayed action valve and a four way valve.
The present invention differs from the aforementioned device in that the traveling fulcrum point is not entirely linear throughout its traverse. Also, in the present invention the primary mechanical advantage is achieved when the traveling fulcrum point comes to rest, whereas in the device of U.S. Pat. No. 4,442,581, the mechanical motion stops whenever the traveling fulcrum denoted by numeral 44 reaches either end of the sliding chamber that guides the fulcrum 44. Further, the present invention does not have the disadvantage associated with hydraulically activated devices.